As an example of a mobile communication system to which the present invention is applicable, 3rd Generation Partnership Project (3GPP) Long Term Evolution (hereinafter, referred to as ‘LTE’) and LTE-Advanced (hereinafter, referred to as ‘LTE-A’) communication systems are briefly described.
One or more cells are present in one Base Station (BS). A cell is set to use one of bandwidths of 1.25 MHz, 2.5 MHz, 5 MHz, 10 MHz, and 20 MHz to provide a downlink (DL) or uplink (UL) transport service to several UEs. Different cells may be set to provide different bandwidths. The BS controls data transmission/reception for a plurality of UEs. The BS transmits DL scheduling information with respect to DL data to inform a corresponding UE of a data transmission time/frequency domain, coding, data size, and Hybrid Automatic Repeat and reQuest (HARQ)-related information. In addition, the BS transmits UL scheduling information with respect to UL data to a corresponding UE to inform the UE of an available time/frequency domain, coding, data size, and HARQ-related information. An interface for transmitting user traffic or control traffic may be used between BSs.
Although radio communication technology has been developed up to LTE based on Wideband Code Division Multiple Access (WCDMA), demands and expectations of users and service providers are continuing to increase. In addition, since other radio access techniques continue to be developed, new technical evolution is required to secure future competitiveness. Decrease of cost per bit, increase of service availability, flexible use of a frequency band, simple structure, open interface, and suitable power consumption by a UE are required.
Recently, 3GPP has been establishing a standard task for a subsequent technique of LTE. In this disclosure, such a technique is referred to as ‘LTE-A’. One of the main differences between an LTE system and an LTE-A system is system bandwidth and the introduction of a relay node.
The LTE-A system is aimed at supporting a broadband of a maximum of 100 MHz and, to this end, the LTE-A system is designed to use a carrier aggregation or bandwidth aggregation technique using a plurality of frequency blocks. Carrier aggregation employs a plurality of frequency blocks as one large logical frequency band in order to use a wider frequency band. A bandwidth of each frequency block may be defined based on a bandwidth of a system block used in the LTE system. Each frequency block is transmitted using a Component Carrier (CC).